In the summer after 15 minutes, the
average temperature in the hot water tank is still 95 degrees,
(15 gallons @ 120 degrees and 15 gallons @ 70 degrees),
although the temperature coming out will still feel hotter,
since the water is not completely mixed. (The hot water
draws from the bottom of the tank where it is hottest, and
the cold water supply comes in to the top).
In the winter when the supply water is
colder, after the same shower the average water temperature
will be only 80 degrees, (15 gallons @ 120 degrees, and
15 gallons @ 40 degrees), a big difference. The hot water
tank is still functioning properly, but because the water
coming in is so much colder, the hot water runs out faster.
A 30gallon GAS hot water tank will reheat completely in
about 45 minutes. A 30 gallon ELECTRIC hot water tank will
take 1.5 hours. |